Fully Thermal-Evaporated Perovskite Light-Emitting Diodes with Brightness Exceeding 240 000 Nits

Thermally evaporated perovskite light-emitting diodes (PeLEDs) have emerged as a promising technology for next-generation display applications. However, achieving high luminance remains a critical challenge. In this study, a significant enhancement in the luminance of fully vacuum-evaporated PeLEDs is demonstrated by optimizing both the crystallinity of perovskite films and hole injection efficiency. A lateral 0D/3D Cs₄PbBr₆/MA_xCs_1-xPbBr₃ heterostructure is achieved via co-evaporation of MABr (MA⁺ = CH₃NH₃⁺), CsBr, and PbBr₂. Theoretical calculations indicate that MAPbBr₃, with its lower formation energy, preferentially forms and serves as a nucleation site for the growth of high-quality MA_xCs_1-xPbBr₃, significantly improving crystallization. Excess CsBr and PbBr₂ react to form Cs₄PbBr₆, which passivates defects and confines excitons, thereby enhancing photoluminescence efficiency. The resulting perovskite films exhibit suppressed non-radiative recombination. Additionally, hole injection and transport efficiency are improved through p-type doping, ensuring sufficient carrier injection for high-luminance emission. As a result, the optimized PeLEDs achieve a maximum brightness of 246, 211 cd m⁻², representing the highest level reported to date for thermally evaporated PeLEDs. These findings underscore the potential of thermally evaporated perovskites for high-brightness display and lighting applications.